This invention relates to injection devices useful for injecting large animals while the operator is standing a safe distance from the animal. It is particularly useful with livestock such as cattle, hogs, horses or the like.
Most livestock is inoculated with serum against common animal diseases. If the inoculation can be accomplished while the animal is still small (especially hogs), such vaccination poses no problem. However, the young offspring of large animals such as cattle or horses may be relatively large.
Injection of such animals--and certainly of adult animals--can obviously be dangerous. Therefore, a number of devices have been proposed to keep the animal at a distance from the user of the device. Some of the devices have used a hypodermic needle on the end of a wand. Most such devices used the thrust by the operator as the force by which the serum would be forced through the needle. However, when the same force is being used to push the needle through the skin of the animal and to eject the liquid from the syringe, there is always considerable degree of spillage.
The present invention uses the thrust by the operator to force the needle through the animal hide, but then uses an exterior force--preferable compressed air or other gas--to operate the syringe. An easily operated valve means is conveniently located so that a simple press of the thumb causes the plunger of the syringe to force the serum through the hypodermic needle.